Since the beginning of time humans have tended to do what feels good — an impulse controlled by the brain. Now, neuroscientists are starting to unravel how something that was a positive impulse thousands of years ago can be detrimental to human surivival today. In a fascinating report entitled The Pleasure Principle which aired last night on CBC NEWS The National, correspondent Kelly Crowe takes a journey deep inside the human brain with behavioral neuroscientist Richard Beninger of Queens University. Together they peel pack the mysterious secrets of pleasure, reward, and the most powerful chemical in the human body — dopamine.